In the past, arc fault protection systems have been designed to detect and mitigate destructive arcing in electrical power systems. One approach employs light sensors to detect a magnitude of light intensity present in the system and compare the magnitude to a fixed threshold to determine whether the detected light is indicative of an arc fault. When an arc fault is detected, the arc protection system indicates such and a protection device is actuated to mitigate the arc.
Generally, the systems provide a relatively low sensitivity threshold to detect the presence of an arc fault event before it becomes too destructive. However, during operation of the electrical power system, the light sensors may detect light from sources that are not related to destructive arcing such as, for example, switches, lamps, or the environment. Detection of light from these other sources can erroneously actuate the protection device (i.e., nuisance tripping). This erroneous actuation of the protection device is exacerbated by the need to set the system to be relatively sensitive to light.
While arc protection systems have been designed to have different light sensitivity levels at the time of manufacture, there is a potential that a user may install a system having the wrong sensitivity level. Moreover, over time, the operating conditions of an electrical power system often changes due to, for example, corroded, worn or aged wiring, connectors, contacts or insulation, loose connections, wiring damaged by nails or staples through the insulation, and electrical stress caused by repeated overloading, lighting strikes, power surges, etc. As a result of such changes in the operating conditions of an electrical power system, an arc protection system that once was suitable to detect arc faults may experience unacceptably frequent nuisance tripping of the protection device.